Caltech Grad Student Awarded Google PhD Fellowship

Erika Ye wants to know what current quantum computers can do

Caltech graduate student Erika Ye has been awarded a Google PhD Fellowship that will support her work on quantum computing. Ye, who is in her third year at Caltech, is one of 39 recipients of the fellowship this year worldwide.

The program was started in 2009 "to recognize and support outstanding graduate students doing exceptional research in computer science and related disciplines," according to a post on the Google Research blog announcing the awarding of the fellowship.

Ye, who is co-advised by Professor of Mechanical Engineering and Applied Physics Austin Minnich, Bren Professor of Chemistry Garnet Chan, and Bren Professor of Theoretical Physics Fernando Brandao, will attempt to discover what current quantum computers can do that classical computers cannot.

Taking advantage of the unique properties of quantum mechanics, quantum computers can, in theory, perform certain tasks faster and more efficiently than classical computers. Quantum computers have so-called quantum bits, or "qubits," that are capable of simultaneously representing the "1" and "0" bit values of classical computing language, a property known as superposition. In addition, qubits can become entangled with one another, such that knowing the state of one gives some knowledge of the states of the others.

"There's been a lot of really good theoretical work on down-the-line algorithms that assume we have an infinite number of qubits, but right now we only have 50 to 100—and there are some big issues with dealing with quantum 'noise' that knocks qubits out of superposition," Ye says. "So, we have to ask, what can we do with these small-scale quantum computers?"

Ye's approach is to find ways that quantum computers can enhance classical computation.

Right now, Ye is focusing on computational chemistry—particularly, calculating the behavior of electrons in complex molecules, which ultimately could provide detailed information about reaction rates or how enzymes in cells work.

"There are a lot of methods and approximations one can use that are good enough for most chemical systems. But there are many interesting materials that these methods cannot yet accurately capture. The hope is that with a quantum computer we can gain insight on the underlying physics of these more exotic materials," Ye says.